Multifunctional pyrazines

ABSTRACT

Certain novel dicyano- and tricyano-pyrazines are obtained by replacing one or two cyano groups of tetracyanopyrazine. The compounds are fluorescent and can be used to prepare polymers.

Unite States Patent [1 1 [111 3,

Donald Dec. 23, 1975 MULTIFUNCTIONAL PYRAZINES 3,763,161 10/1973 Hartter 260/250 R [75] Inventor: geerlmis Scott Donald, Wilmington, OTHER PUBLICATIONS [73] Assignee: L Du Pom de Nemours and Castle, ed., Pyridazines, Heterocyclic Compounds,

Company, Wilmington, Del.

Filed: Oct. 5, 1973 Appl. No.: 403,867

Related US. Application Data Division of Ser. No. 232,207, March 6, 1972, Pat. No. 3,814,757, which is a continuation-in-part of Ser. No. 133,724, April 13, 1971, abandoned.

US. Cl. 260/250 BN Int. Cl. C07D 241/02 Field of Search 260/250 BN, 250 B, 250 R References Cited UNITED STATES PATENTS 8/1963 Vest 260/327 Vol. 28, Interscience, N.Y., 1973 pp. 2528, 202-203.

Rappoport, The Chemistry of the Cyano Group, Interscience N.Y., 1970, pp. 168, 169, 202-203.

Primary Examiner-Richard J. Gallagher Attorney, Agent, or Firm-Anthony P. Mentis [57] ABSTRACT Certain novel dicyanoand tricyano-pyrazines are obtained by replacing one or two cyano groups of tetracyanopyrazine. The compounds are fluorescent and can be used to prepare polymers.

5 Claims, N0 Drawings MULTIFUNCTIONAL PYRAZINES RELATED APPLICATION This is a division of application Ser. No. 232,207 filed Mar. 6, 1972, now US. Pat. No. 3,814,757, which is a continuation-in-part of application Ser. No. 133,724 filed Apr. 13, 1971 ,now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention Tetracyanopyrazine having the formula is described and claimed in coassigned patent application Ser. No. 54,617 filed July 13, 1970 now US. Pat. No. 3,763,161. It serves as the starting material for making the dicyanoand tricyano-pyrazines embraced in the generic formula below. The products are useful as fluorescent materials, for curing epoxy resins, and for the production of polymers.

2. Description of Prior Art The unique properties of per-compounds have been known for a number of years. These include the numerous fluoro compounds that have come to constitute a large field of organic chemistry. A somewhat smaller field is composed of percyano and polycyano compounds, as reviewed by T. L. Cairns and B. C. McKusick in Angewandte Chemie 73', 520 (1961 Many of the percyano compounds exhibit the properties of undergoing nucleophilic displacement of a cyano group, a reaction that is unique to percyano compounds. An interesting example is the reaction:

CN NC c=c +C H -,OH NC CN NC oC,H v No art appears to exist, however, showingthe compounds of the present invention.

DESCRIPTION OF THE INVENTION The invention comprises compounds having the general formula below and the methods of making them. The new compounds have the formula:

2 b. Y and Z, alike or different, are selected from OR". NH N.HR, N(R) NRR and and wherein each R, alike or different, is alkyl of lj to .7

4 carbons or alkenyl of 2 to 4 carbon atoms;

R is aryl, aralkyl or alkaryl of 6 to 10 carbon I of a compound of the formula ZH, where Z has the values given above under (a) and with the proviso that Z mayalso equal OH. The specific compound where Y is CN and Z is OH is the subject of another copending application of assignee now US. Pat. No.

3,763,161. The reaction proceeds smoothly and in high yield and may be shown as:

NC 'CN Nc. N z

IOI HZ IO]: HCN (A) we ,u CN no N cm The optimum reaction conditions vary rather widely depending on the specific nucleophilic reagent employed. Thus, the temperature of reaction ranges from 60C for the highly reactive primary and secondary amines to reflux temperatures for the alkanols, e.g., from about 25C to C. Aromatic amines and carbanions react readily at 60C to 50C, and preferably at 0 to 5C.

Reaction times similarly range widely from instantaneous for the alkyl amines to several hours at reflux for the higheralcohols. For example, the methanol reaction is complete in 30 minutes at 25C while 20 hours is required for 2-butanol. The rapid amine reactions are best controlled by slow addition of the amine at low temperatures. Generally, reactions are complete in 0.5 to 24 hours and preferably are planned to be complete in 1-5 hours.

The more nucleophilic compounds such as ammonia and primary and secondary amines present a special case and, when present in excess, displace more than one cyano group as in equation NC N cu 1 2 IO]: +2uz OI aucn (B) No N on N N CN or OR with R having the values set out above and HZ is used in at least two molar equivalents.

In the replacement of a single cyano group, care must be exercised to avoid the presence of unreacted amine during workup of the reaction mixture.

The reaction of ammonia and primary amines can be conveniently monitored by following color changes during the addition of the amine. The addition is preferably slow and the reaction generates a deep red color that fades as the displacement occurs. Addition of amine in excess of one equivalent produces a permanent coloration. The color change is much like that of an acid-base indicator in acidimetric measurement.

reactions are generally run at 25l50C, and preferably at 60 l C. The reactivity of alcohols is strongly affected by steric considerations. Thus, primary alcohols are most active, followed by secondary alcohols.

The reactivity of alcohols can be greatly enhanced by the addition of a basic catalyst such as a trialkylamine.

This modification is of particular value when it isdesired to displace two cyano groups as in reaction B.

As previously noted, an excess of alkylamine is to be avoided in reaction A, and preferably exactly one mole of reagent per mole of tetracyanopyrazine is used. Aromatic amines and alcohols are generally used in proportions equimolar with, or in excess of, the tetracyanopyrazine. This will usually result in employment of l molar, and preferably ll .2 molar, equivalents of aromatic amine or alcohol per mole of tetracyanopyrazine.

Reaction B, which is limited to ammonia, primary and secondary aliphaticamiries, and base-catalyzed alcohols, requires at least two molesof reactant per mole of tetracyanopyrazine, and generally 2-6 moles per mole of tetracyanopyrazine are employed. Preferably, 34 moles are used in this reaction.

Certain carbanions can also replace a cyano group of tetracyanopyrazine as shown in Example 12 in which the triethylammonium salt of 2-nitromethyl-3,5,6- tricyanopyrazine is prepared. Analogous active methylene compounds such as malonic esters, CH(COOR) cyanoace tic esters, CH (CN)COOR; l,3-diketones, CH- (COR e.g., cibenzoylmethane; nitroacetic esters, CH (NO )COOR; and analogs react similarly with tetracyanopyrazine. The radicals R and R have the values previously set forth.

Pressure is not a critical factor in the practice of this invention and, while the reactions 'are generally carried out at ambient pressure, they may also be carried'out at pressures considerably below atmospheric, e.g., at about mm when employing gaseous reagents. Similarly, the reactions may be carried out at pressures above atmospheric, e.g., at pressures as high as several hundred atmospheres.

Suitable solvents include tetrahydrofuran, acetone, dioxane, acetonitrile, ethyl acetate and other lower esters such as glycol dimethyl ether (glyme) and glycol diethyl ether.

SPECIFIC EMBODIMENTS OF THE INVENTION The following examples illustrate specific embodiments of the invention. All parts are by weight unless otherwise stated.

EXAMPLE 1 2,6-D1amino-3,S-dicyanonyrazine N c I01 21m:

N CN

To a stirred pool of ca. 25 ml of liquid ammonia under nitrogen was added dropwise over a period of 0.5 hour a solution of 10.0 g (0.0556 mole) .of tetracyanopyrazine in ml of dry tetrahydrofuran. The solution turned deep red with the first drop. After the addition was complete, the deeply colored solution was stirred under a stream of nitrogen, filtered and washed with fresh tetrahydrofuran. This slightly grey material (442 g) is relatively pure 2,6-diamino-3,5- dicyanopyrazine. Evaporation of the filtrate yielded 4.52 g of darker product which is only slightly less pure product.-

Recrystallization from dimethylformamide yielded long,slightly yellow needles containing solvent of crystallization which was removed by heating at C or higher at20 mm Hg for several hours. This material began to darken to a red solid above 300C and did not melt below 400C.

IR (KBr): 2.89 p., 2.97 p., 3.07 ,u, 3.14 a, 5.98 ,u, 6.10 p. (NH 4.48 p. (C E N); 6.48 p. (conjugated C=C and/or C=N).

UV UlULL (6 (E 222mg (6 33 ,600).

HRMS: molecular ion, measured calcd. m/e l60.0497.

Anal. Calcd. for C H N C, 45.00; H, 2.52; N, 52.48; Found: C, 45.29; H, 2.79; N, 52.46.

EXAMPLE 2 2,6-Diamino-3,S-dicyanopyrazine A stream of dry ammonia was passed over a rapidly stirred solution of 20.0 g (0.11 1 mol) of tetracyanopyrazine in 475 ml of tetrahydrofuran for 0.75 hour. A deep red color was generated which faded as the ammonia was consumed. When the color persisted, the reaction was complete. The exothermic reaction was maintained below 25C by ice-bath cooling during the initial part of the addition. The reaction mixture was evaporated to dryness on a rotatory evaporator giving, after drying at 100C in a vacuum oven, 18.1 g of grey powder which was relatively pure 2,6-diamino- 3,5dicyanopyrazine.

In addition to the procedures set out in Examples 1 and 2, 2,6-diamino 3,5-dicyanopyrazine can also be prepared by ammonia displacement of the 6-cyano group in 2-amino-3,5,6-tricyanopyrazine as set out in Examples 3 and 4 below. The 2-amino-3,5,6-

tricyanopyrazine compoundran'd its'synthesis, is .disclosed in commonly assigned patent application Ser. No. 54,617, filed in the name of Donald R. Hartter on July 13, 1970 now US. Pat. No. 3,763,161.

6 drofuran and isolation .ofv the precipitated product as described above.

EXAMPLE 5 2 6-1315 (dimethy -l amino -3 5-di'dyanopjyrazine.

lE AMPLEs Nb N Na iin. IO]: was i nc trot .,N c.,N, cu

Y= Z=Nll To a magnetically stirred pool of liquid ammonia- 2,6-Diamino- 3,5-dicyanopyrazine A l-liter, 3-necked, round-bottom flask equipped with an addition funneL-thermom'eter, magnetic stirring bar and gas inlet tube was-charged with 100 ml of dry tetrahydrofuran and cooled to 2C in an ice bath.

After passing dry ammonia over the "rapidly stirred solvent for 5 minutes, the" dropwise addition of 40.0 g

"(sagas N Moss);

A250-ml, 3 -ne c-lted,.round bottomed flask'equip ped with, a magnetic stirring bar, thermometer,- gas inlet tube and gas outlet was charged with ml of anhydrous tetrahydrofuran. Gaseous dimethylamine was passed into the reaction vessel until the volume of the tetrahydrofuran solution had increased by several milliliters. The gas inlet tube was replaced with an addition funnel containing 5.0: g (0.0278 mol) of tetracyanopyrazine in 25 ml of tetrahydrofuran. A 20C rise in temperature accompanied the initial addition of of aminotricyanopyrazine in 400ml of drytetrahydrofuran was begun at sucha rate that the temperature did not rise above 8C. Ammonia was passed over the solution continuously during the addition and was continued for 1 hour at 5C after the addition was complete. The cold slurry was poured into 800 ml'ofice water giving a dark suspension which was filtered with vacuum. The filter-cake was washed with distilled water until the washes were clear and almost colorless. The washing was continued with acetone until the washes were only slightly yellowfabout 350 ml being required. The innfrared spectrum of the pale grey solid was identical with that of pure 2,6-diamino-3, 5-dicyanopyrazine. After drying overnight at 100C at caf 30 mm Hg, 31.0 g (82.2%) of material was obtained. So'rne additional material can be recovered from the water/tet rahydrofuran solutions by evaporation'of the tetrahy- 'the solution and an ice bath was applied to maintain the temperature at about 15C during the remainder of the addition. A yellow precipitate began to form after 1 ml of the tetracyanopyrazine-tetrahydrofuran solution had been added. After the addition was complete, the slurry was stirred for an additional 15 minutes and was filteredfTh e pale yellow solid obtained was washedonce with 'cold tetrahydrofuran and air-dried giving 4.87-g of material melting at 2l 3.0 :-2l4.0C and showing only" one spoton a thin layer chromatogram (Silica Gel G);

using acetone, chloroform, benzene and acetonitrile. Evaporation of the filtrate yielded 0.92 g of only slightly less pure material. Recrystallization of 2.0 g 'of the purer material from 20 ml of chloroform gave 1.05 g of 2,6-bis(dimethylamine)-3,5 dicyanopyrazine as shiny yellow plat'e's; rn'p 2l4.02l5.0C. Crude yield,

IR (KBr): 3.38 ,u., 3.42 p. (sh) (saturated CH); 4.51

,u (C E N); 6.36 p. (sh), 6.44 ,u. (conjugated cyclic Anal. Calcd. for C H N z C, 55.54; H, 5.59; N, 38.87; Found: C, 55.03; H, 5.68; N, 39.21.

+ 2ii cii NC- N on no 11 ON 5 I01 2(cH3)2im NC N CN 7 EXAMPLE 6 2-(N-methyl-11-phenylam1no)-3 5, 6-tricyanopyrazine NC N CN NC NC 21' on To a vigorously stirred solution of 20 ml of N- methylaniline in 30 ml of anhydrous tetrahydrofuran was added dropwise a solution of 5.0 g (2.78 mmol) of tetracyanopyrazine in 40 ml of anhydrous tetrahydrofuran at such a rate that the temperature did not rise above 26C. The addition required 1.5 hours and the reaction was complete at this time. The reaction mixture was poured into 500 ml of water and a small A solution of 5.0 g of tetracyanopyrazine in 50 ml of absolute methanol was allowed to stand under nitrogen at room temperature. The reaction was complete within 2 hours. Further reaction did not occur after 20 hours at room temperature or even after 20 hours at reflux. The solvent was stripped off on a rotatory evaporator leaving a slightly yellow oil which crystallized upon scratching with a glass rod. This material melts at 90.0.91.0C. Material recrystallized from diethyl ether/petroleum ether melts at 93.594.5C.

IR (KBr): 3.37,u(CH); 4.43 ,u (C E N); 6.41 ,u., 6.71 p. (conjugated C=C and/or C=N); 8.12 pl. (=C OC).

UV A,,,,,, 323K112 (6 13,500); 259m,u (6 14,300).

HRMS: molecular ion, measured m/e, 185.0346; calculated m/e, 185.0338.

NMR (CDCl;,): singlet, 4.37 8.

Anal. Calcd. for cal 113N 01 C, 51.89; H, 1.62; N, 37.77; Found: C, 51.44; H, 1.60; N, 38.15.

EXAMPLE 8 2-Anilino-3,5,6-tr1cyanooyrazine 1 30; 325 u 3 4( (Saturated To an ice bath-cooled-solution of 6.0m] (65.6 mmol) 4.45 ;1. C N); 6.22 p., 6.38 ,u (sh); 6.43 [.L, 6.58 p. and 6.68 p. (aromatic C=C, conjugated cyclic C,uC and C=N); 12.80 1.1., 12.85 12.92 1.1., 14.15 ,u, 14.30 p. (monosubstituted aromatic).

UV 8m 360 my. (sh) e 7,250 307 mp.

NMR: (acetone-d singlet, 7.51 6 (5H); singlet, 3.61 6 (3H).

Anal. Calcd. r0 c mu c, 64.60; H, 3.08; N,

of aniline in 40 ml of anhydrous tetrahydrofuran was added dropwise with stirring a solution of 10.0 g (55.6 mmol) of tetracyanopyrazine in 40 ml of anhydrous tetrahydrofuran at such a rate that the temperature did not rise above 5C. After stirring for an additional 15 minutes, the reaction mixture was poured into 300 ml of ice water. Crystallizationof the precipitated oil was induced by scratching to produce an orange solid which was collected by filtration and washed with water. After air-drying overnight, the material was dried in a vacuum oven at 100C for 2 hours giving 13.45 g (54.7 mmol, 98.2%) of material whose infrared spectrum is identical with recrystallized material. Recrystallization of 13.0 g of the crude product from ml of acetonitrile gave 1 1.3 g of orange crystals of 2-anilino- 3,5,6-tricyanopyrazine, mp 234C (decomp.).

IR (KBr): 2.96 LL (NH); 3.26 u. (=CH); 4.44 ,u (C E N): 6.20 t, 6.37 t, 6.48 11., 6.66 ,u. (conjugated, cyclic C=C and C=N; may include --NH); 12.98 .4, 14.42 1., 14.58 ;1. (monosubstituted aromatic).

UV nuua 400ITIIL(6 3 1801/0!6 235m (6 10,900).

NMR (acetone-d broad absorption centered at 9 2.82 5 (1H), complex pattern centered at 7.56 (5H) typical of N-substituted anilines.

Anal. Calcd. for C H N C, 63.40; H, 2.42; N, 34.10; Found: C, 63.34; H, 2.13; N, 34.73; C, 63.66; H, 2.13; N, 34.68; C, 63.26; H, 2.42.

EXAMPLE 9 2- A1 1y lami no- 5, 5 6-tr1cyanooyra zine NC N cit I I NO N cu To a solution of 5.0 g (0.0278 mole) of tetracyanopyrazine in 50 ml of anhydrous tetrahydrofuran at --50C was added dropwise with stirring overa period of minutes a solution of 2.0g (0.0350 mole) of allylamine in. 10 ml of anhydrous tetrahydrofuran. A transient, deep red color which persists near the end of the addition is produced by each new drop of the allylamine solution. After the addition was complete, the

deep red solution was poured into 500 mlof water. The

NMR (acetone-d6) multiplet, 4.258 (2H); multiplet,

5.258 (2H); multiplet, 5.95 (1H).

Anal. Calcd. for C H N C, 57.14; H, 2.88;iN,-'

39.99; Found: C, 56.76; H, 2.88; N, 40.03; C, 56.76; H, 2.68; N, 39.68.

NC N

I NC N A slurry of 5.0 g (0.0278 mole) otitetracyanopyrazine in ml of 2-butanol was stirred at ambient temperature for 22 hours during which time'complete solution occurred. The slightly yellow. solution was diluted with petroleum ether and cooled in mice bath to form 2.94 g of white plates which were collected by filtration; mp 75.0 to 760C. Recrystallization from diethylether/petroleum ether gave material melting 76.5-77;0C. The original mother liquors were evaportedto' dryne'ss under 'vacuum yielding 1.92 g of material which'was separated. into l.79"'g of the title compound as adiethylether soluble fraction and mg of diethylether insoluble material'who se infrared spectrum suggests an iminoester. Total yield of 2-(2; but'oxy)-3,5,6-tricyanopyra2ine was 4.73 g, 75%.

uv A,,,,,,. ""';325 ,i E =13,000 260' (c 15,106 NMR (acetone-d triplet, J 7.0 Hz, 1.081(3H);

doublet,

(2H sextet, J 6 Hz, 5,435 (1H).

Anal. Calcd. for CHH9N5O: c, 58.14; 14,3.99'; N,

30.82; Found: C, 58.5l; H, 4.15; N, 30. 8l.'

In addition to the alcohols shown in Examples 7 and I 10, other primary andsecondary alcohols which may be used in the reaction to displace one or two cyano groups of tetracyanopyrazine, include for example, ethanol, l-propanol, 2-propanol, l"-butanol, 2-butanol,

benzyl alcohol, fi-phenethyl alcohol, 3-phenylpropanol, 4-phenylbutanol, etc.

EXAMPLE 1 l Q-Benzvlamiro-Lj, G-trfl. cyanopyrazine no N cu NC N NHCHZQI I01 CHaNHz I01 NC N an no N on EXAMPLE l0 2-(2-Butoxy)-3,5,6-tricyanopyrazine NC on HCN 4 HON lR (nujol): 4.43p. (weak); 6.42p., 655 7.50%

To a solution of'5100 g (2.78 X mole) of tet- Anal. Calcd. for C H, 1 1 O C, 53.33; H, 5.40; N, rac'yanopyrazine i'n'50'mlof dry'tetrahydrofuranat ca.- 31.11 Found: C, 51.91; H, 4.90; N, 31.58 52.28 5.02 -65C was added dropwise with stirring a solution of 31.79. 3.00 g (2.80 10' mole of benzylamine in 10 ml of 5 dry tetrahydrofuranSA transient deep red color was EXAMPLE 13 2, 6- Di (a My lamina)-5,5-d1cyanopyra::ine

NC on M N fix QHN/V/ NC N on I NC 11 CN produced aseach drop contacted the cold solution. A solution of 3.5 g (61.4 mmol) of allylamine in 100 When the addition was complete, the clear, orange ml of dry tetrahydrofuran was added over a 40-minute solution was allowed to warm slowlytoroom temperaperiod to a stirred solution of 5.0 g (27.8 mmol) of ture and was then evaporated to dryness yielding 7.01. tetracyanopyrazine in 15 ml of tetrayhydrofuran. lnigof a,yel1o w solid melting at 180-18-2C; Crystallizatially each drop of amine solution generated a deep red tion from nitromethane gave large yellow crystals of color and the temperature rose to 43C. This tempera- 2-ber'izylamino-3-,5,6-tricyanopyrazine, i mp ture prevailed throughout the addition. Considerable 183.0-184.0C with decomposition. darkening occurred toward the end of the reaction. 1R (nujol): 3.00., 4.45 6.23 6.50p., 7.90 7.95 4,: Stirring was continued for minutes after the addtion 13. 1 8 ,,,.14 22;;. v v p L a was completed followed by evaporation of the reaction UV- Mm I pL (E ,340); 297mg. (e mixture to dryness. The solid residue was redissolved in 24,900); 230 h) (6 9,850), 3O tetrahydrofuran, treated with Darco, filtered and evap- NMR Cfi fiul S nglet, 4.85 (2H); multiplet, orated .to dryness. The yellow solid product (6.5 g) was 7318 (SH); broad absorption, 8.676 (11-1). 1, crystallized from methylene chloride to give 0.76 g of A C d f C H N C, 641,]; H, 3 10; N 2,6-di(allylamin0)-3,5-dicyanopyrazine, melting at 32.29; Found: C, 64.45; H, 2.90; N, 32.94; C, 64.07; zlgiclsealed tube under nitrogen).

H, 3.10; N, 32.42. Y

' EX'AMPLE l2 hviamnonium Sa 11; 0t 2-Nit r omethyl- 3, 5, 6- .tr1cya'nopyraz1ne A solution of 5.00 g (0.0278 mole) of tetand CH); 4.51 p. (-C E N); 6.06 p.(vinyl); 6.24, racyanopyrazine in ml of dry tetrahydrofuran was 6.45, 6.50 p. (conjugated C=C and/or C i N); 9.97, cooled to 0C and 2.00 G (0.0328 mole) of nitrometh- 10.20, 10.69, 10.88 p. (vinyl). ane was added in one portion. To the stirred solution was added dropwise 3.30 g (0.0328 mole) of triethyl- UV? (G: 18,000); 288 (6: 21,600); amine at such a rate that the temperature did not rise 238 above 5C. The dark solution was evaporated to dryness l i h trimethylammonium 2 4 5 HRMS: molecular ion observed m/e 240.1 16,

tricyanopyrazinyl nitromethanide as a relatively pure, calcddark red solid, mp. 1 l9.0-120.0C. (decomposition).

IR (KBr); 3,27, 357 3 398 (related to NMR: (dimethylsulfoxide, multiplet 3.70-4.20 8 (Br m-1+ 449 C= 47 166 #1 (21-1, allyl); mu1tiplet4.88-5.356(21-1, terminal olefin); 6.65 1. (C=C and/or C=N). complex 5.50-6.30 8 (1H, allyl); multiplet 7.90-8.30 6

uv A,,,,,,. 423mg. (6 45,300 254mg. (6 65 H. NH)- NMR(acetone-d.;) triplet, 1.4l8(3H);quartet,3.436 Anal Calcd' for CWHWNB: 6000; 500;

(2H); broad singlet, 6.405 1H); singlet, 7.15s 1H). 35-00; Found: C, 59-41; 5-10; N, 3527- 'IR (KBr): 2.98 L(NH); multiplet 3.25-3.40 11. (=CH f Thiee grams of the tetracyanopyrazine-N.N dime A slow stream of monomethylamine was passed over thylaniline charge-transfer complex in 20 ml ofmethaa rapidly stirred solution of 5.00 g (2.78 X 10" mol) of 1101 was reflijXedlunder N for 8 hours; the" blue color tetracyanopyrazine in 45 ml of dry tetrahydrofuran for gradually faded. Upon cooling overnight large pale 1 hour. A yellow precipitate formed which was colbrown plates formed. These were collected,and recryslected by filtration, washed with cold tetrahydrofuran Q tallized from methanol to give l.l7.g (87%) light tan and air-dried giving 910 mg of nearly pure 2,6-bis(N- crystals of. 2,6-dimethoxy-3,S-dicyanopyrazinef" mp methylamino)-3,5-dicyanopyrazine. Recrystallization 158.1 to 159.8C. from dimethylacetamide gave the analytically pure A l, c l d, f C l-1 N C, 50,53; H, 3,18; N, material which does not melt below 350C. 2947; F d; C, 50,37; H, 3,20; N, 29.70.

IR(KBr): 2- 1 H); 1 14 (saturated IR (KBr): 3.36 1 (aliphatic CH), 4.47,u.(nitrile), and 4.49 p. (C E N); 6.19 p. and 6.42 p. (conjugated C=C 829 u h /o 7-O 1 W b 8),-v UVA 257111 1 (k 79.4; e 15,000 322mg.

MW 3701M l (k(ke= 16,100). 1 ,7 2 m =7 2 m1i NMR (CDCl TMSi 4.23s (singlet, 0011 HRMS: molecular C8H8Nfi su Mass spectrum molecular ion calcd. for C H N O 188.0812; calcd..rn/e, 188.0815); observed m/e, 83 and m/e 190 Found; 190 O49l 68 for M(90 CH and M-(9O 1- CH NH), respectively. i EXAMPLE 16 "These fragments evidence the cleavage;

i i I Q I in A'stream of'anhydrous methylamine was passed over 31 m N 11 1011 a vigorously stirred'soliition of 5.0 0'g (2.78 X l0 mol) l g of tetracyanopyrazine in ml of anhydrous tetrahy- 8' I 5 drofuran cooledtoO in an ice/salt bath. deep red d! CN 90 g y color was generated at'the vortex which was initially dissipated into the solution. When the red 'color per- 1 sisted the reaction was immediately quenched by pour Anal fl s fi 5105; 4283 ing the reaction mixture into 400 ml of water.-A yellow Found: 51-05; 447? l l 55 solid formed which was collected by filtration,'washed with water and air dried giving 4.97 g (97%) of Z-(N- 1 methylamino)-3,5,6-tricyanopyrazine whose infrared EXAMPLE 15 spectrum is virtually .identical with the. infrared spectrum of 'analyticallyp'ure material obtained by crystalli- 26'DimethOXy'3s'dicyanopyrazine zation from benzene, mp l68.0169.0,C.

, Y z ocH R Br): 3.001114%); 3.38. (saturated cm; 5

NC N CN H=1CO N OC 1 I i C C C,H,-,NMe,, C' C I CHHOH l ZHCN C C C 1 NC N CN NC N CN EXAMPLE 17 2-dimethy 1nm1no-3 5, 6-t r1 cyanopy rnzine NC N ,cN

THF NC 92 NC l on (CH3)2NH T c p cw Y CN; 2 (011 9 To a well-stirred solution of 5.00 g (27.8 mmole) of tetracyanopyrazine in 50 ml of dry tetrahydrofuran at C. was added over a period of 1 hour by volatilization from a cold trap, 2.50 ml of anhydrous dimethylamine. An acetone/dry ice condenser was used to contain the dimethylamine in the reaction vessel until it was absorbed and consumed. After an additional hour the reaction mixture was poured into 250 ml of ice water and the yellow solid which formed was collected by filtration and wshed with water. After drying there was 5.10 g (92.7% crude yield) of material whose infrared spectrum is identical with that of analytically pure material recrystallized from 5:1 carbon tetrachloride/- chloroform, mp l00-l01.

IR (KBr): 340a, 3.48,u., 4.48;.t, 6.54p., 6.72

UV k 410mg, (6 4180); 310 ma (6 24,200); 242 mp. (e 11,400)

NMR (acetone-d singlet, 3.558.

Anal. Calcd. for C H N C, 54.54; H, 3.05; N, 42.41; Found: C, 54.74; H, 3.02; N, 43.04 I

EXAMPLE 18 2-amino-3, 5-dicyano-6-d1methy1aminopyrazi r g N CH 'ca): (cH)N 32 32 NC NC ature. After an additional hour the reaction mixture was evaporated to dryness on a rotory evaporator giving 1.94 g (89% crude yield) of an off-white solid whose infrared spectrum is the same as that of the analytical sample obtained by recrystallization from benzene, mp 202.0-203.0.

IR (nujol): 2.95p.; 3.051;; 3.l5,u.; 4.5g; 6.1g; 6.45

UV L 365mp. (e 15,100); 285mg. (6 19,600); 237m,u (e 30,300)

NMR (acetone-d singlet, 3.388 (6H); broad peak at ca. 78 (2H) Anal. Calcd for C l-EN C, 51.05; H, 4.28; N, 44.66; Found: C, 50.97; H, 4.22; N, 44.98

HCN

EXAMPLE 19 Z-nmino- S-dicyano-b- (N-methylani11no)pyra.z1ne

To a stirred solution of 3.00 g (l 1.5 mmol) of 2-( N- methylanilino)-3,5,6-tricyanopyrazine (Example 6) was added 1.5 ml of 30% aqueous ammonium hydroxide in one portion. The solution warmed slightly and became dark. After 10 minutes the reaction mixture was poured into 200 ml of water whereupon the dark color dissipated and a tan solid formed which was collected by filtration and washed with water. After drying there was 2.43 g (84.4% crude yield) of material which was recrystallized from 85 ml of chloroform with DARCO treatment giving 2-amino-3,5,-dicyano-6-(N- methylanilino)pyrazine as yellow microcrystals mp 230.0230.5.

lR (nujol): 2.90 14 3.0g; 4.5g; 6.2a; 6.48;; 7.17 .t; 7.88

UV A 367m (6 17,800); 289mp. (6 14,100); 238m (5 28,200)

NMR (acetone-d singlet, 7.508 (5H); singlet, 3.488 (3H); broad absorption centered at ca. 78 (2H).

Anal. Calcd for C H N z C, 62.39; H, 4.03; N, 33.58; Found: C, 62.00; H, 3.98; N, 33.93.

The following examples illustrate utility of the compounds of the invention.

EXAMPLE A Fluorescing Agents "-17 All of the pyrazines prepared by this invention fluoresce. A test for fluorescence brighteners is? H N NR2 ,1 N Two milliliters of a dimethylformamide solution of 1 I 5 No I 0.75% of the test compound is added to 125 mlof a 0.4% detergent solution in distilled water; This bath is heated -to 130F and a 5-g swatch of fabric immersed therein for minutes. The swatch then removed, rinsed twice and air-dried. v I

The instant compounds were tested on a multifiber test fabric that contained the following fibers; nylon, Orion, Dacron, cotton.

The 2-me th oxy-3,5,6-tricyanopyrazirie (Example i showed affinity for and brightening of nylon. i

The product of Example 1 (2,6-diamirio-I3,5- dicyanopyrazine) showed affinity for brightening action was definite;

' Polyamide from 2,6-D1piperid1n0-3gj -dicy ariopyzcazine and Toluene Diisocyanate w I .liic

EXAMPLE B Curing of Epoxy Resins A mixture composed of 16.9 parts of 2 ,6-diamino -y 3,5-dicyanopyrazine, 2.76 parts of Diuron [N ,N-(,dime thyl)-N-dichlorophenyl] urea, which is a curing agent for epoxy resins), and 100 parts of epoxy resin sold by i Dow Chemical Co. as Dow QX-3599, wasappliedbe tween cold-rolled steel sheets and cured by heating at 250F for 90 minutes. The resultant bond had a shear strength of 2700 psi.

EXAMPLE C Polymer Formation The 2,6-diaminoand 2,6-di(alkylamino)-3,5- dicyanopyrazines are useful in polymer formation. For

example the equation below depicts the formation of a polymer comprising units of the structure shown.

I excess ,N-H-

. with l liter of boiling tetrahydrofuran and the insoluble material (10 g) was removed by filtration. On cooling in ice, the filtrate deposited 24.4 g of light yellow product, 2,6-dipiperidino-3,S-dicyanopyrazine, mp

NMR (CDCl 3.7-4.15 (m, 2H, CH5); 2.8-3.25 (m, 2H, CH5); 1.838 (s, 1H, NH).

IR (KBr): 2.90 1, 3.08 1. (NH); 4.5111 (C E N); 6.42;/., 6.5011. (C=C, C=N).

UV A 378mp. (e 13,000); 300mpt (e 19,500); 262mg. (6 25,700); MS M m/e 298.1659, calcd. for C H N M m/e 298.1654, m/e 243.

Anal. Calcd. for C H N C, 56.36; H,- 6.08; N, 37.57; Found; C, 56.55; H, 6.02; N, 37.88; 'C, 56.27; H, 6.23; N, 38.07. I l I To --a slurry of 4.15 g (0.0139 mole) of 2,6- dipiperidino-3,S-dicyanopyrazine in 15 ml of dimethylformamide was added 2.43 g (0.0139 mole) of toluenediisocyanate in ml of dimethylformamide, followed by a -ml dimethylformamide wash. Stirring was continued for 4 hours, and the polymer was then precipitated into methanol to give 6.10 g (93%) of light yellow polymer, ninh 0.38, 0.1% in dimethylformamide, C. A tough, self-supporting film was cast and dried at 80C overnight under vacuum. Differential "scanning calo-' rimetry showed a possible glasstransitiontemperature at 46C and an exotherm at 225-280C. Differential thermal analysis from -40 to +150C showed no significant thermal event. The film was drawn 3X at 250C (stick temperature 280C) and the T /E /M; of the undrawn and drawn film are 8500 psi/5.6%/246,500 psi and 9900/6.3%/274,800.

Anal. CalCd for C23H24N10O2I C, H, N, 29.65; Found: C, 57.87; H, 5.25; N, 29.11 C, 57.96; H," 5.30; N, 29.54. J

EXAMPLE E The bath was removed, and stirring was continued for another 2.5 hours. The polymer was precipitated by pouring into methanol, washed with water, aqueous bicarbonate solution, water, and methanol and dried. A total of 7.85'g of very light yellow polymer was obtained, ninh 0.43, 0.1% in hexafluoroisopropanol, 25C. The polymer was insoluble in amides, but was soluble in acidic solvents, hexafluoroisopropanol, and formic acidfOnly brittle films could be cast from hexafluoroisopropanol. Differential thermal analysis showed a possible T,, at 273C, exotherm at 337C. Differential scanning calorimetry showed an exotherm at 225C but no T Anal. Calcd. for C H N O C, 61.68; H, 4.71; N, 26.17; Found: C, 61.44; H, 4.69; N, 25.81.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

The compound of claim 1 which is 2-anilino-3,5,6- tricyanopyrazine.

Polynmidc fro-"n 'lcrephthaloyl Chloride and 2,6-D1(lp1per-idy1)- L "1-61 cvnnonvrnzine A solution of 5.97fg 0.02 mol) of diamine in 70 all of dry'dimethylacetamide was cooled to 78C. and

406 g 0.02 mol) of terephthaloyl chloride was added water bath, and stirring was continued for minutes.

all at once. The dry-ice bath was, replaced with an ice- 3',j 6 tricyanopyrazine 4. The compound of claim 1 which is 2-allylamino- 3,5,6-tricyanopyrazine.

5. The compound of claim 1 which is 2-benzylamino- 

1. A COMPOUND SELECTED FROM THE GROUP CONSISTING OF 2-(NMETHYL-N-PHENYLAMINO)-3,5,6-TRICYANOPYRAZINE, 2-ANILINO3,5,6-TRICYANOPYRAZINE, 2-ALLYLAMINO-3,5,6-TRICYANOPYRAZINE, AND 2-BENZYLAMINO-3,5,6-TRICYANOPYRAZINE.
 2. The compound of claim 1 which is 2-(N-methyl-N-phenylamino)-3,5,6-tricyanopyrazine.
 3. The compound of claim 1 which is 2-anilino-3,5,6-tricyanopyrazine.
 4. The compound of claim 1 which is 2-allylamino-3,5,6-tricyanopyrazine.
 5. The compound of claim 1 which is 2-benzylamino-3,5,6-tricyanopyrazine. 